1. Field of the Invention
The present invention relates to an optical information regeneration recorder, an optical information recording method and a signal processing circuit and, more specifically, an optical information recording method and an optical information regeneration recorder, and a signal processing circuit, and a recording reproduction program, and information recording medium in which recording conditions according to compatibility between a drive and a medium may be optimized.
2. Description of the Related Technology
In recording of an optical information recording medium represented by CD-R or DVD-R (hereinafter, referred to as “media”), compatibility between target media and recorders used for recording (hereinafter, referred to as “drive”) differs depending on the combination. It is because of the fact that the optimum recording conditions vary according to the type of recording material of which the media is formed or layer difference at the time of manufacture as factors on the media side, and the fact that optimum conditions vary according to the type of a pick up or a semiconductor laser which constitutes the drive or assembly variations at the time of manufacture as factors on the drive side. Actually, there exist recording conditions which are suitable for the respective combinations taking the causes on both sides into account as a compound factor.
Therefore, the related art employs an approach to store ID information indicating the type of the media and being able to be identified from the drive side on the media side, and store recording conditions prepared for the type of the media on the drive side. At the time of actual recording, the ID information of the media is read from the media loaded in the drive, and the recording conditions which are associated with the ID information (referred to as “write strategy”) are used.
However, with this approach in the related art, although suitable recording conditions may be selected to some extent for verified and known media, the prepared recording conditions may not support unknown media which are not verified. Even with the known media, there are cases in which the prepared recording conditions cannot support such known media depending on the change of recording environment such as recording speed, disturbance and change with time.
Examples of such known approach which supports the unknown media include approaches disclosed in JP-A-2003-30837 and JP-A-2004-110995. In paragraph 0020 in JP-A-2003-30837, there is a statement “detects the phase gap with respect to the channel clock in every write pattern. The recording correct parameter adjustment part 12 optimizes the light waveform rule on the basis of the detected result in the phase gap detector 11 . . . ”, and an approach to detect and correct the phase gap through comparison with the channel clock is disclosed.
In the paragraph 0024 in the same document, there is a statement “Subsequently, a test pattern for determining the light waveform rule is recorded. Then, the area in which the test pattern is recorded is reproduced, and the relation between the prepared light waveform rule and the amount of phase gap is inspected. In other words, the amounts of phase gap in the respective combinations of the lengths of various marks and various spaces immediately before these marks are measured. The light waveform rule in which the amount of phase gap is zero is predicted from the measured amount of phase gap to determine a desired light waveform rule . . . ”, in which an approach to measure the amount of phase gap for each mark and space combination to predict the light waveform rule in which the amount of phase gap is zero is disclosed (see FIG. 16 and FIG. 20).
According to the approach stated in JP-A-2003-30837, correction on the basis of the phase gap of the write pattern is performed, and hence it is an effective approach for optimizing the strategy.
In paragraph 0045 in JP-A-2004-110995, there is a statement “a top pulse which corresponds to 3 T period and a non-multi pulse which corresponds to 8 T period are integrally (continuously) generated”, and in paragraph 0046 in the same document, there is a statement “the laser power of the write pulse is regulated in two levels, and the optimum power is obtained when the ratio between the laser power (the peak value of the top pulse) Ph and the laser power (the peak value of the non-multi pulse) Pm is optimum . . . ”, in which the effectiveness of optimization of the ratio of Ph/Pm is suggested.
On the other hand, employment of a PRML (Partial Response and Maximum Likelihood) method is considered as a code identification method of a high-density record system using a blue laser. In the PRML method, the code identification is performed on the basis of amplitude information of an RF signal acquired by reproducing the write pattern. Therefore, in order to achieve a high-quality recording, setting of the recording conditions using an evaluation index different from a slice method in the related art is required.
Here, JP-A-2004-13978, JP-A-2004-280876, JP-A-2003-15129, JP-A-2004-63024, JP-A-2004-213759 and JP-A-2004-152473 are known as methods of setting the recording conditions on the basis of the amplitude information of the RF signal.
In JP-A-2004-13978 and JP-A-2004-280876, a method of determining conditions of a first pulse, an intermediate pulse and a last pulse with the index of asymmetry is disclosed, a method of determining conditions of a write pulse on the basis of the difference between an ideal waveform with an assumption of PRML and a reproduced waveform acquired from an actual record is disclosed in JP-A-2003-15129, JP-A-2004-63024 and JP-A-2004-213759, and a method of determining a start position of the first pulse with the index of asymmetry and the widths of the first pulse and the intermediate pulse with the index of jitter is disclosed in JP-A-2004-152473.
A method disclosed in JP-A-2002-197660 is known as a method of performing code determination using a bitabi decoder.
In JP-A-2002-197660, a method of identifying the code in the reproduction signal and detecting amplitude and asymmetry of a reproduction signal by synchronizing output from the bitabi decoder which receives supply of digitally sampled reproduction signals and the timing-regulated digital reproduction signal using a delay circuit is disclosed.
In JP-A-2003-15129 and JP-A-2004-63024, a method of evaluating the amount of reference from ideal by the comparison with an ideal signal which is originally to be detected is described. The method of this type is described in the documents shown above and also in JP-A-2002-197600 and JP-A-2003-303417, and is a method effective for evaluating and setting high-density recorded data such as Blue standard.
However, in the method disclosed in JP-A-2003-30837, the strategy stored in the drive in advance is fine adjusted as in the related art, and hence a desirable record characteristic is hardly satisfied for the media which does not match the strategy stored in advance.
In the method disclosed in JP-A-2004-110995, the initial values of Ph and Pm are provisionally set on the basis of the values stored in the drive or the media and then the ratio of Ph/Pm is obtained as described in the paragraph 0067 in the same document. Therefore, the desirable record characteristic is hardly satisfied for the media which do not match the provisionally set value as in the case of the JP-A-2003-30837.
In the methods disclosed in JP-A-2004-13978 and JP-A-2004-280876, the conditions of the first pulse and the last pulse are determined at the same time using the same index. Therefore, the shortest pulse, which is most likely to be affected by error, is not optimized, and hence is affected easily by the disturbance, so that the probability of occurrence of error increases. Therefore, in these methods, a recording margin is large and hence a high-quality record system can hardly be provided.
In the methods disclosed in JP-A-2003-15129, JP-A-2004-63024 and JP-A-2004-213759, since only the pulse shapes which are generally known are corrected, and hence it is difficult to specify which part of the pulse shape is effective for which index. Therefore, the recording margin is large and hence the high-quality record system can hardly be provided as in the case of JP-A-2004-13978 and JP-A-2004-280876.
In the method of JP-A-2004-152473, although the start position of the first pulse is determined with the index of asymmetry, the widths of the first pulse and the intermediate pulse are determined simultaneously with the index of jitter. Therefore, the recording margin is large and hence the high-quality record system can hardly be provided as in the case of JP-A-2004-13978 and JP-A-2004-280876.
In the method disclosed in JP-A-2002-197660, it is assumed that the quality of the reproduction signal has at least a quality which may be decoded through the bitabi decoding. Therefore, when the quality of the reproduction signal is low, the code is erroneously identified, and hence there remains a problem that the amplitude level of the data code to be obtained cannot be detected. Specifically, erroneous identification may often occur for the unknown media in which the write strategy is not registered in advance in a memory of the recorder.
In order to cope with increase channel bit rate in association with increase in density of the recording data, when the signal length is short, samples cannot be obtained by the number sufficient for the level detection with a low-speed A/D converter, and cost increase is resulted when a high-speed A/D converter is used.
The evaluation of the amount of reference from the idea described in JP-A-2003-15129, JP-A-2004-63024, JP-A-2002-197600 and JP-A-2003-303417 is an evaluation and setting method using evaluation indices for the recording state represented by SbER and PRSNR. Such method is effective for total evaluation of the recording state, and, however, is subject to mutual affect such that when one of the parameter conditions is optimized, the other parameter condition which is adjusted previously is deviated from the optimum state, and hence it is not a satisfactory method for partly or respectively optimizing a plurality of parameters possessed by a recording power or write pulse conditions.